Circular dichroism (CD) measurements are one of the most valuable sources of structural and conformational information on solutions of chemical and biochemical compounds. Recent improvements in instrumentation have further enhanced the usefulness of this technique in chemical and biochemical research. This proposal is for the purchase of a modern CD spectropolarimeter to be used by a large number of researchers. Problems under investigation by the prime user group are 1) structures of myosin and actin and muscle contraction, 2) structural analysis of ubiquitin-protein conjugates, 3) complexes of drug molecules and carcinogens with double stranded DNA, 4) oligomerization of melittin and peptides from HIV gp41, 5) eye lens proteins and other proteins of the visual system, 6) electrostatic properties of the alpha-helix, 7) two dimensional structure of apolipoprotein B on the surgace of the low density lipoprotein, 8) molecular analysis, synthesis, and folding of defensins, and 9) synthesis of sequence specific nucleases. The proposed purchase of CD equipment will fulfill acute research needs for this type of insurumentation by NIH- supported investigators at UCLA.